Abstract
<jats:p>In the process of designing buildings and structures, the issue arises of ensuring their mechanical safety under accidental loads. Furthermore, existing buildings and structures are often subjected to technogenic impacts that may lead to complete or partial failure of the structural system. To provide a quantitative characterization of the resistance of load-bearing structures to such factors, the concept of survivability has been introduced in the modern scientific literature. However, the formalization of survivability in the form of specific quantitative indicators remains a pressing and insufficiently explored problem for both steel and reinforced concrete structures. This study proposes a methodology for computing the probabilistic survivability index for frame structural systems. The calculation is based on a modified model of classical reliability theory, which assumes that the failure of the frame system occurs through the formation of a mechanism with a minimum number of plastic hinges. The assessment of structural failure or component degradation is performed on an energy basis using the J-integral. To analyze the scatter of random parameters, statistical modeling based on empirical data is employed. The article provides examples of survivability index calculations. Practical implementation of the proposed method has demonstrated its effectiveness, allowing it to be recommended for evaluating the mechanical safety of steel and reinforced concrete frame structures, including cases with increased responsibility requirements and specific robustness criteria against progressive collapse.</jats:p>